Predicted Total Lung Capacity Ratio between Donors and Recipients Does Not Predict Outcomes in Non-Volume Reduced Lung Transplantation

Abstract

Purpose A predicted total lung capacity (pTLC) ratio of 1.3 between donor and recipient has been described before as beneficial regarding survival after lung transplantation. Here, we wished to analyze data from our center regarding the effect of pTLC ratio on short- and long-term outcome following non-volume reduced lung transplantation. Methods Between 01/2005 and 08/2018 a total of 1506 lung transplantations were performed at our center. Predicted TLC-ratio was calculated retrospectively and short- as well as long-term outcome parameters were recorded. 156 transplantations with volume reduction procedures or lobar transplantations were excluded from the analysis. Results Median pTLC-ratio of all 1350 transplantations was 1.02 (IQR 0.96-1.08); (female 1.06, IQR 1.0-1.14, n=625; male 0.99, n= 725, IQR 0.91-1.05). Median follow-up time of the cohort was 41.3 months. The analysis revealed no significant correlation between pTLC ratio and mechanical ventilation time (p=0.09), postoperative ICU stay (p=0.19) or total hospital stay (p=0.26). Recipients showing PGD grade 2 or 3 (ISHLT 2005 criteria) at any time after transplantation had a median pTLC ratio of 1.02, this not being statistically different to recipients without signs of PGD at any time point (median pTLC ratio 1.02) (p=0.21). When dividing transplants into subgroups according to the respective donor/recipient pTLC-ratio (0.9-1.0; 1.0-1.1; 1.1-1.2; 1.2-1.3; 1.3-1.4) no survival difference between the different pTLC groups was detectable (p=0.24). Upon subanalysis of recipient's underlying diseases, no significant correlations between pTLC ratio and %predicted FEV1 at any time after transplantation were seen in COPD, IPF or IPAH patients. The cohort of cystic fibrosis patients showed a significant negative correlation between higher pTLC ratios and %predicted FEV1 at time of discharge from the initial hospital stay following transplantation (p=0.01), however, this was not detectable anymore in spirometry 1 year after transplantation (p=0.21). Conclusion Focusing only on those transplants performed without surgical donor lung size reductions, specific donor/recipient pTLC ratios did not impact short- and long-term outcomes in this single-center analysis. This suggests a wider range of pTLC-ratios may be safely used for allocation in lung transplantation.